A. Field of the Invention
A rapid pressure rise relay is a device used on liquid cooled electric power transformers, to detect excessive rates of pressure rise within the tank as a result of internal arcing. This arcing occurs because of faults such as winding insulation breakdown. The output of the rapid pressure rise relay is commonly used to trip the transformer circuit and thus de-energize the transformer to prevent further damage.
B. Description of Prior Art
Mechanical devices for rapid pressure rise detection have been and continue to be a part of the protection practices for electric power transformers. In U.S. Pat. No. 4,074,096, granted on Feb. 14, 1978 in the name of Robert F. Romanowski, a bellows controlled sudden pressure rise relay is described. Other rate sensitive mechanical devices are known. These devices use mechanical components to determine the rate of change of pressure and then operate micro-switches to provide an electrical output. The momentary switch closure is commonly applied to a seal-in relay to maintain the tripped status.